On to the actual tow cable. I was first referred to some braided metal cable produced specifically for modelmakers, but it was much too thick, and didn't coil around the spool at all. I found my answer in a picture hanging kit. The braided wire for hanging pictures on a wall was almost perfect in the smallest size, the 10-50 lb strength. I ran it through a candle flame to give it the appropriate worn/stained appearance.
Next, some of the most critical scratchbuilding of the project, the sling. I tried various materials to simulate the heavy duty rubber straps, including black duct tape, black latex gloves and even bicycle inner tube. The latter had the perfect appearance but alas, was far too thick.
I found the answer in black party balloons. The rounded part had too many curves to use, but the balloon necks had barely enough length of flat material.
Add to that the chains on each side and the effect exceeded my hopes.
On the end of the chains are hooks; these I made from reshaped sections of paperclip, then attached to the chains and painted worn dark metallic. After this I was VERY relieved and pleased with the result.